Sooner or later you will fill up your iPad. I noticed this when I got the alert that I did not have room to update my apps. I started by deleting apps I did not use. But that didn't do it. I didn't know how to figure out what was hogging the space.
My Apple genius friend Paul showed me how. Go to Settings > General > Storage and you can see what is using up the most space. In this case I have 5 Zinio magazines that are taking up the most space. Also need to make some hard decisions on lots of other things too. But at least now I know where to start.